Backdoor access to Techboard/Syac devices

# SPDX-FileCopyrightText: 2014 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.105059");
  script_tag(name:"cvss_base", value:"10.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_version("2023-07-27T05:05:09+0000");

  script_name("Backdoor access to Techboard/Syac devices");

  script_xref(name:"URL", value:"http://blog.emaze.net/2014/07/backdoor-techboardsyac.html");

  script_tag(name:"last_modification", value:"2023-07-27 05:05:09 +0000 (Thu, 27 Jul 2023)");
  script_tag(name:"creation_date", value:"2014-07-08 15:03:46 +0200 (Tue, 08 Jul 2014)");
  script_category(ACT_ATTACK);
  script_tag(name:"qod_type", value:"remote_vul");
  script_family("General");
  script_copyright("Copyright (C) 2014 Greenbone AG");
  script_dependencies("find_service.nasl");
  script_require_ports(7339);

  script_tag(name:"impact", value:"Clients can leverage this service to execute arbitrary commands on the
  underlying Linux system, with root privileges.");
  script_tag(name:"vuldetect", value:"Send a special request to port 7339 and check the response.");
  script_tag(name:"insight", value:"Affected devices include a backdoor service listening on TCP port 7339.");
  script_tag(name:"solution", value:"No known solution was made available for at least one year since the disclosure
  of this vulnerability. Likely none will be provided anymore. General solution options are to upgrade to a newer
  release, disable respective features, remove the product or replace the product by another one.");
  script_tag(name:"solution_type", value:"WillNotFix");
  script_tag(name:"summary", value:"Backdoor access to Techboard/Syac devices");

  exit(0);
}

port = 7339;
if( ! get_port_state( port ) ) exit( 0 );

soc = open_sock_tcp( port );
if( ! soc ) exit( 0 );

send( socket:soc, data:'KNOCK-KNOCK-ANYONETHERE?\x00' );
buf = recv( socket:soc, length:12 );

close( soc );

if( ! buf || strlen( buf ) != 12 ) exit( 0 );

if( hexstr( substr( buf, 8, 12 ) ) == "000aae60" )
{
  security_message( port:port );
  exit( 0 );
}

exit( 0 );